pub(crate) mod common {
    use serde::Serialize;

    pub fn opp(i:i32) ->i32 {
        i*i
    }

    pub fn add(a:i32, b:i32) ->i32  {
        a+b
    }

    #[derive(Serialize)]
    pub struct Person {
        pub(crate) name: String,
        pub(crate) age: u32,
    }
}
